A. Elmagarmid, Y. Leu, W. Litwin, and M. Rusinkiewicz. Proceedings of the sixteenth international conference on Very large databases, page 507--518. Morgan Kaufmann Publishers Inc., (1990)
C. Godart, O. Perrin, and H. Skaf. 9th Int. Workshop on research Issues on Data Engineering Information technology for Virtual Entreprises (RIDEVE'99), (1999)
K. Abbott, and S. Sarin. Proceedings of the ACM Conference on Computer- Supported Cooperative Work (CSCW '94, page 113--120. Chapel Hill, North Carolina, ACM Press, (1994)
U. Dayal, M. Hsu, and R. Ladin. 17th International Conference on Very Large Data Bases, September
3-6, 1991, Barcelona, Catalonia, Spain, Proceedings, page 113-122. Morgan Kaufmann, (1991)